You dont say if the rs232 connections are to be concurrent or not,if not than all thats needed is a multiplexor which would be used to distribute the one rs-232 connection to multiple points with a single control word.If you need concurrent connections then there dont exist micros with 7 rs-232 ports ,if you dont actualy need the full voltage level conversion which is implied by rs-232 but just the framing and start/stop and parity bits inserting then that could be achived with a custom logic device containing the multiple rs-232 tx/rx units.
I don't know if its deja vu all over again but i am sure someone posted something like this not long ago.
By the way I see that this is your first post so welcome aboard